Tag Archives: University of Southern Mississippi

Nanotechnology-enabled flame retardant coating

This is a pretty remarkable demonstration made more so when you find out the flame retardant is naturally derived and nontoxic. From an Oct. 5, 2015 news item on Nanowerk,

Inspired by a naturally occurring material found in marine mussels, researchers at The University of Texas at Austin have created a new flame retardant to replace commercial additives that are often toxic and can accumulate over time in the environment and living animals, including humans.

An Oct. 5, 2015 University of Texas news release, which originated the news item, describes the situation with regard to standard flame retardants and what makes this new flame retardant technology so compelling,

Flame retardants are added to foams found in mattresses, sofas, car upholstery and many other consumer products. Once incorporated into foam, these chemicals can migrate out of the products over time, releasing toxic substances into the air and environment. Throughout the United States, there is pressure on state legislatures to ban flame retardants, especially those containing brominated compounds (BRFs), a mix of human-made chemicals thought to pose a risk to public health.

A team led by Cockrell School of Engineering associate professor Christopher Ellison found that a synthetic coating of polydopamine — derived from the natural compound dopamine — can be used as a highly effective, water-applied flame retardant for polyurethane foam. Dopamine is a chemical compound found in humans and animals that helps in the transmission of signals in the brain and other vital areas. The researchers believe their dopamine-based nanocoating could be used in lieu of conventional flame retardants.

“Since polydopamine is natural and already present in animals, this question of toxicity immediately goes away,” Ellison said. “We believe polydopamine could cheaply and easily replace the flame retardants found in many of the products that we use every day, making these products safer for both children and adults.”

Using far less polydopamine by weight than typical of conventional flame retardant additives, the UT Austin team found that the polydopamine coating on foams leads to a 67 percent reduction in peak heat release rate, a measure of fire intensity and imminent danger to building occupants or firefighters. The polydopamine flame retardant’s ability to reduce the fire’s intensity is about 20 percent better than existing flame retardants commonly used today.

Researchers have studied the use of synthetic polydopamaine for a number of health-related applications, including cancer drug delivery and implantable biomedical devices. However, the UT Austin team is thought to be one of the first to pursue the use of polydopamine as a flame retardant. To the research team’s surprise, they did not have to change the structure of the polydopamine from its natural form to use it as a flame retardant. The polydopamine was coated onto the interior and exterior surfaces of the polyurethane foam by simply dipping it into a water solution of dopamine for several days.

Ellison said he and his team were drawn to polydopamine because of its ability to adhere to surfaces as demonstrated by marine mussels who use the compound to stick to virtually any surface, including Teflon, the material used in nonstick cookware. Polydopamine also contains a dihydroxy-ring structure linked with an amine group that can be used to scavenge or remove free radicals. Free radicals are produced during the fire cycle as a polymer degrades, and their removal is critical to stopping the fire from continuing to spread. Polydopamine also produces a protective coating called char, which blocks fire’s access to its fuel source — the polymer. The synergistic combination of both these processes makes polydopamine an attractive and powerful flame retardant.

Ellison and his team are now testing to see whether they can shorten the nanocoating treatment process or develop a more convenient application process.

“We believe this alternative to flame retardants can prove very useful to removing potential hazards from products that children and adults use every day,” Ellison said. “We weren’t expecting to find a flame retardant in nature, but it was a serendipitous discovery.”

Here’s a link to and a citation for the paper,

Bioinspired Catecholic Flame Retardant Nanocoating for Flexible Polyurethane Foams by Joon Hee Cho, Vivek Vasagar, Kadhiravan Shanmuganathan, Amanda R. Jones, Sergei Nazarenko, and Christopher J. Ellison. Chem. Mater., 2015, 27 (19), pp 6784–6790 DOI: 10.1021/acs.chemmater.5b03013
Publication Date (Web): September 9, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall. It should be noted that researchers from the University of Southern Mississippi and the Council of Scientific & Industrial Research (CSIR)-National Chemical Laboratory in Pune, India were also involved in this work.

Camouflage face paint which protects soldiers from fire

They are very busy at the Fall 2012 (244th) meeting  of the American Chemical Society. Robert Lochhead, Ph.D., from the University of Southern Mississippi presented research on a new form of face paint(makeup) for the military which not only camouflages soldiers it can, for preciously seconds,  protect them from fire according to the Aug. 22, 2012 news release on EurekAlert,

Camouflage face makeup for warfare is undergoing one of the most fundamental changes in thousands of years, as scientists today described a new face paint that both hides soldiers from the enemy and shields their faces from the searing heat of bomb blasts. Firefighters also could benefit from the new heat-resistant makeup, according to the report.

Robert Lochhead, Ph.D., who presented the report, explained that soldiers have used face paint for centuries for one kind of protection ― to help their skin blend in with the natural environment and shield them from enemies. The new material continues that tradition, but also provides protection from the searing heat of roadside bomb blasts and other explosions that have claimed a terrible toll in Iraq, Afghanistan and other conflicts.

“The detonation of a roadside bomb or any other powerful explosive produces two dangerous blasts,” Lochhead said. “First comes a blast wave of high pressure that spreads out at supersonic speeds and can cause devastating internal injuries. A thermal blast follows almost instantaneously. It is a wave of heat that exceeds 1,112 degrees Fahrenheit. That’s as hot as a burning cigarette. The thermal blast lasts only two seconds, but it can literally cook the face, hands and other exposed skin.”

In an effort to protect soldiers from this threat, the U.S. Department of Defense has been seeking a solution that Lochhead initially regarded as an impossibility: A material that soldiers could smear on their faces like suntan lotion, leaving a coating that although thinner than a sheet of paper, could protect against that intense heat. Dr. Paige Buchanan, Kelli Booth, Michelle McClusky, Laura Anderson and Lochhead were the team that tackled the challenge. Not only did they succeed, but they discovered a formulation that protects in laboratory experiments way beyond the 2-second heat-wave threat from improvised explosive devices and other bombs.

The new camouflage makeup protects the face and hands for up to 15 seconds before its own temperature rises to the point where a first-degree burn, which is a mild burn, might occur. In some tests, the new face paint can protect for up to 60 seconds, which could be important in giving soldiers time to move away from blast-related fires and also for use by civilian firefighters.

I was able to find a few more details about the face paint in an Aug. 22, 2012 transcript of a podcast by Christopher Intagliata for Scientific American,

Conventional camo paint has tiny nanoparticles of pigment. They’re great at reflecting visible light—which is why the paint looks green or black or tan. But the particles don’t reflect longer wavelengths, like heat. To do that, you need larger globs of pigment.

So researchers bundled together a bunch of those smaller particles into chunks the size of grains of sand—large enough for heat rays to bounce right off. And they swapped out the grease for silicone which adds smoothness and spreadability to cosmetics, but won’t catch fire.

There were a number of requirements that the researchers had to meet (from the news release),

The trickiest part was that the University of Southern Mississippi team had to avoid the use of mineral oil, mineral spirits, fatty substances and other traditional hydrocarbon makeup ingredients. Hydrocarbons can burn in contact with intense heat in the flame spectrum. The team turned to silicones, which are not as flammable because they absorb radiation at wavelengths outside of the intense heat spectrum. Silicones have been replacing hydrocarbons in many commercial cosmetic makeup products as cosmetics companies improve products to confer better feel properties and transfer-resistance.

Another challenge was adding DEET, an insect repellent. The military mandates that all camouflage makeups contain 35 percent DEET. “DEET also is flammable, so when the Department of Defense asked us to incorporate it, we didn’t think we could do it,” Lochhead noted. But the team successfully included DEET by encapsulating it in a hydrogel substance, a water-rich material that prevented DEET from catching fire.

There are plans for future applications (from the news release),

It already has passed the preliminary laboratory tests needed to determine whether development should continue. Lochhead’s team also plans tests of the material on other surfaces to try to protect clothing, tents and other items from burning, and a colorless version is being developed for firefighters.

I’m glad to see this innovation which will hopefully cut down on some horrendous injuries.

Here’s final idle thought: I can’t imagine that soldiers use the term camouflage ‘makeup’; I wonder what they call instead?